We have made an alternative estimation of the disappearance rate of ventricular fibrillation (VF) in out-of-hospital cardiac arrest based on data collected from the first 10.966 cardiac arrests in Sweden. In our original analysis published in Resuscitation (2000;4:7–17) we defined VF on arrival of the ambulance crew either based on the initially recorded rhythm or on information that the patient was defibrillated. The latter was included in the definition since we judged information from ambulance crew using automated external defibrillators less reliable with regard to interpretation of the initial rhythm. An alternative approach would be to define initial rhythm only on the basis of information from the initial rhythm regardless whether an automated external defibrillators was used or not. When taking the ‘new’ approach there was missing information in 21% of the cases as compared with 0% in the ‘old’ approach. When estimating occurrence of VF in the remaining 79% we found that 37% had VF on admission ECG. This figure is somewhat lower than the 43% reported in the previous article. According to this ‘new’ approach the disappearance rate of VF would be slightly higher as compared with our previous estimation. This is illustrated in the Fig. 1 where the disappearance rate according to our initial definition of VF is shown as the ‘old’ bars and the disapperance rate according to our new definition of VF is shown as the ‘new’ bars. All patients with probable heart disease (HD). Old and new definition of VF. However, as shown in the figure the estimated occurrence of VF at the time of cardiac arrest remained similar regardless of definition of VF being used.